The New England Journal of MedicineProtection Against Omicron from Vaccination and Previous Infection in a Prison System

In a high-risk population, vaccination was better than prior infection, with incremental increase in protection with additional vaccination doses.

• Prior infection in unvaccinated individuals ranged from 16% to 49% vs omicron infection
• Versus unvaccinated, previously uninfected individuals, vaccine effectiveness at preventing omicron infection ranged from 19% to 83% with 2 doses and 41% to 88% with 3 doses
• Three vaccine doses offered significantly more protection than two doses, including among previously infected persons